Was on a tour a month ago and on the way back the magneto just stopped working. Car runs on BAT but nothing from the mag.

I’ve done some searching and checked the continuity from the mag post to the switch, then to the coil box. That is good.
Next I checked the magneto itself with a 1156 bulb and it in fact lights up.
What Am missing? Any ideas as to why it runs on BAT but not on MAG?

If that is as bright as your magneto will light the bulb, I suspect a weak mag. But, if it ran good on mag while on the tour, then I'd suspect a piece of lint, or trash is lodged against the mag post. Unscrew the mag post, shine a light through the hole, and see if there is anything that might be breaking contact with the solder blob. A mirror may be required to see the blob. Keep your fingers crossed. https://youtu.be/QnMUPNFbVWQ

I pulled the probe out. It was clean. I even stretched the spring a bit to make sure it had good contact. I will have to check the actual solder blob and make sure it is clean as well. My father just acquired the T last year so we don’t have much of a history on the magneto itself.

I would say if that is just at idle I don't think it's too bad. Might just be the switch it self need cleaning or attention. With the bulb attached like it is, do a check with an analog meter set to AC. Hook the leads from the meter to the same points as the bulb. Do this at different RPMs. This will not work with a digital meter unless you have are real high quality meter that can filter out the back ground noise from the magneto.

the later switches (oval plate in the dash) had issues on their contacts. And IIRC no one repoped these (someone should have!!!). The earlier switches were easier to rebuild, and the coilbox switches were EXTREMELY easy to rebuild

It may also be a wiring issue - wires on T's vibrate and break. Run a jumper to check if it's OK, that will tell you if your wires are OK. IF you rewire and you still have issues, then you have to redo your switch...

BTW the biggie isn't the switch itself, but when you unbend the tabs holding the switch together they break. I'm working to try to redo the tabs (or) make a repair that while not appearing factory spec, work (which to me, with a T, is the most important issue). Because somehow, somewhere, these 25-27 switches will all die... and we need some wahy to keep this resource running.

Part of the issue is that mag runs up to 64 VAC (what I've measured, YMMV, I heard some run +90VAC)). That's a lot of volts to throw into the connectors in those switches, engineered for 1 amp at 24 volts. I have been toying with gold contacts (godawful expensive but will take the heat) but if I had switches I would play with other materials like Silver, Platinum, et al.

Serious - it is one of the few, rare, weak points of Henry's Unversal cars. I KNOW the answer is out there (even if it's a double-relay system like on modern iron) but the resources are hard to come by.

Thats why I tell people how to jump their cars on mag (Jumper cable 14- ga, direct mag poist to coil box) because if they have one of these 80-90year old corroded internaly switches, they can still get their car running,

the later switches (oval plate in the dash) had issues on their contacts. And IIRC no one repoped these (someone should have!!!). The earlier switches were easier to rebuild, and the coilbox switches were EXTREMELY easy to rebuild

It may also be a wiring issue - wires on T's vibrate and break. Run a jumper to check if it's OK, that will tell you if your wires are OK. IF you rewire and you still have issues, then you have to redo your switch...

BTW the biggie isn't the switch itself, but when you unbend the tabs holding the switch together they break. I'm working to try to redo the tabs (or) make a repair that while not appearing factory spec, work (which to me, with a T, is the most important issue). Because somehow, somewhere, these 25-27 switches will all die... and we need some wahy to keep this resource running.

Part of the issue is that mag runs up to 64 VAC (what I've measured, YMMV, I heard some run +90VAC)). That's a lot of volts to throw into the connectors in those switches, engineered for 1 amp at 24 volts. I have been toying with gold contacts (godawful expensive but will take the heat) but if I had switches I would play with other materials like Silver, Platinum, et al.

Serious - it is one of the few, rare, weak points of Henry's Unversal cars. I KNOW the answer is out there (even if it's a double-relay system like on modern iron) but the resources are hard to come by.

Thats why I tell people how to jump their cars on mag (Jumper cable 14- ga, direct mag poist to coil box) because if they have one of these 80-90year old corroded internaly switches, they can still get their car running,

Susanne, Ben Martin rebuilds these switches. He did a great job on mine. Sometimes you just need to take the switch apart and bend the contact arms a bit to increase spring tension on the contact.